Periodically cam operated switch



July 4, 1967 J. KELLEIGH 3,329,782

PERIODICALLY CAM OPERATED SWITCH Filed Oct. 15, 1965 2 Sheets-Sheet 1 INVENTOR.

Walaa al a 19a BY W W 4% United States Patent 3,329,782 PERIODICALLY CAM OPERATED SWITCH Waldo J. Kelleigh, Wayland, Mass., assignor to Electrical Apparatus Company, Inc., Boston, Mass., a corporation of Massachusetts Filed Oct. 15, 1965, Ser. No. 496,338 20 Claims. (Cl. 200--61.41)

The field of this invention is that of circuit makers and breakers of the type which periodically operate switch contacts by means of motion detecting feeler and movement transferring cam apparatus. Many devices of this type are commonly also referred to as limit switches.

Objects of the invention are to provide switches of the above type for exact and easily adjustable timing correlation between opening and closing positions of control contacts and the movement of a mechanical detector or feeler element caused by a controlling body such as an object moved by machinery, or a moving component of machinery;

To provide such switches which are peculiarly suited for applications requiring a light controlling force;

To provide limit switches with adjustment provisions permitting extensive overtravel or pretravel contact operation of contacts closing and opening once during complete travel of a detector arm capable of complete 360 rotation, clockwise or counterclockwise;

To provide for convenient and yet precise contact adjustment assuring maximal timing precision;

To provide for easy accessibility, adjustment and exchange of components of the switch which if desired can be enclosed in a securely sealed housing;

To provide for the use of standard leaf spring precision contactors in control apparatus of the present type;

To provide a device of this type which incorporates mechanical elements of excellent friction properties and with precise cooperation as to transfer timing throughout the kinematic train involved;

To provide for easy and conveniently observable adjustment of control points from the outside of the housing including timing and duration of actuation by a control initiating moving body, zero adjustment of the switching cycle, sensitivity adjustment, and pretravel and overtravel setting; and

To provide apparatus of this type which is very versatile in adaptability to a large number of modes of operation and is yet simple, reliable and comparatively inexpensive in manufacture and assembly.

The substance and nature of the invention can be briefly summarized in some of its aspects as follows.

Switches according to the invention comprise mounted on frame means, usually a housing, the following principal subassemblies. Detector means which extend into the path of a moving body which may be an article fed to or discharged from machinery or a component of a machine itself; transfer means receiving rotary motion from a cam of the detector means and imparting it to a second cam; the switch means proper; switch means and switch actuator means interposed between the switch means and the transfer means and serving as an intermediary between the second cam and the switch means. In the preferred embodiment described, the detector means includes a shaft pivoted on the frame and carrying detecting feeler the follower means and the detector cam means; the motor means is capable of maintaining contact between the follower and the detector cam and also capable of rotating the shaft through power transmission by way of the follower means and detector cam means. The switch means is preferably of the resilient contact blade type such as described in my Patent No. 2,825,778 of Mar. 4, 1958. The switch actuator has preferably a resilient lever arm parallel to the blades of the switch and an insulating operator which deflects a switch blade upon deflection of the actuator lever by the cam on the arbor.

These and other objects and aspects of the substance of the invention will appear from the following description of a preferred embodiment illustrating the novel characteristics of the invention.

The description refers to drawings in which FIG. 1 is a front elevation of a switch according to the invention with the detector feeler means partly broken away;

FIG. 2 is a section on lines 2-2- of FIG. 1;

FIG. 3 is a section on lines 3-3 of FIG. 2;

FIG. 4 is a section on lines 44 of FIG. 3 showing the switch proper and only that part of the housing to which the switch is adjustably attached;

FIG. 5 is a section on lines 33 of FIG. 2, similar to FIG. 3, but showing zero limiting spokes which are omitted from FIG. 3 for the sake of clarity; and

FIG. 6 is a partial section on lines 66 of FIG. 2, but showing a modified spring motor arrangement.

As shown in FIGS. 1 and 3, this embodiment of the invention has a housing with a metal part 10 which is open at both ends where it is closed by top and bottom covers 11 and 12 of high grade insulating material. The covers are fastened to the metallic housing proper by means of ears 11.1 and 12.1, and screws 11.2 and 12.2, as shown in FIG. 3. The bottom cover 12 has preferably a strained release bushing 12.5 of conventional design which admits the wires leading to the three terminals of the switch which will be described herein below. The main housing 10 has two openings, 14 for illuminating the switch from the outside, and 15 for observing the illuminated contacts. Both windows are closed with a suitable transparent material. The front of the main housing also has an opening 16 for the independently pivoted detector or feeler shaft, which opening can be sealed with an O-ring in conventional manner. By appropriately sealing the covers 11 and 12 to the housing 10 and by providing gaskets for the other openings to be described below the housing can be completely sealed. For purposes to be described herein below, the front of the main housing portion 10 also has a tapped hole for a Zero adjustment spindle, a similar hole for a spring sensitivity adjustment spindle, two holes for contact closure adjustment screws, and three capped holes for angle stop pieces, marked and 270. The meaning of these informatory legends, indicated in FIG. 1, will become apparent from the following description. The housing carries on the inside two bearing blocks 17 and 18 fastened with appropriate screws, two of which can also serve to carry an angle stop :piece, and on the outside, an indicator 58, all of which will be described below.

The detector means assembly has a shaft 21 pivoted in the above-mentioned bearing blocks 17 and 18 and extends through the likewise above-mentioned opening 16. The provision of special bearing blocks permits the use of any suitable bearings for minimal friction and practically unlimited bearing life, and of a convenient seal for the shaft. A detector head or collar 22 is secured to the shaft 21 such as by means of a set screw 22.1 such that it can be conveniently rotated for any desirable angle adjustment. The head 22 has a slot 21.2 for the detector arm or feeler 23. For many uses of the present switch but not necessarily, this is a flexible steel blade. For example, it can also be a stiff rod or an air current sensitive vane, depending on the use of which the switch is put. Since the slot 21.2 is diametrically of the head 22 it can be shifted to extend on either side, again depending upon the use to which the switch is put. A set screw 23.1 is provided to fixate the blade in its slot. To the other end of the shaft 21 is fastened the detector cam 24. This cam consists of an eccentrically mounted disk 24.1 adjustably fastened to the shaft 21 for example by a set screw 24.2 and carrying a cam roller 24.4 on a pivot stud 24.5. The shaft 21 also carries a zero adjustment hub 26 (FIG. with two wings 26.1 and 26.2 and a strip 26.3 (FIG. 2) for fastening it to the shaft 21 by means of a screw 26.4. The zero setting wings cooperate with an L-shaped zero stop rod 26.5 carried by a zero setting spindle 26.6 which extends through the front wall with an outside threaded off set part having an hexagonal Allen type recess. As indicated at 26.7, a nut permits fixation of the spindle 26.6 against rotation whereas, upon loosening the nut the spindle can be rotated by means of an Allen wrench in order to rotate the stop rod 26.5. The shaft 21 also carries a stop pin 28 intended for cooperation with a stop 29 which can be attached with one of the three stop carrier screws 29.1, 29.2, 29.3 (FIGS. 1 and 2). These stop screws define stop positions marked 90, 180 and 270 as above mentioned. The stop 29 has a washer 29.1 and a turned up nose 29.2 as shown in FIG. 2. The nose 29.2 can be rotated on its screws in such a manner that its contact with the pin 28 defines exact deflection angles of blade 23.

The transfer means assembly has an arbor 31 which is parallel to shaft 21 and similarly pivoted in bearing blocks 17 and 18. It has a follower rod 32 fastened in a hole of the arbor by pressing it thereinto, and a spring rod 33 extending opposite thereof and similarly fastened to arbor 31. The follower rod 32 contacts the roller 24.4 of the detector cam against which it is pressed by means of a spring 33.1 the tension of which can be adjusted by means of a spring adjustment finger 33.2 which is fastened in a hole of a sensitivity adjustment spindle 33.5 which is rotatably fastened to the front wall of the housing in a fashion similar to that explained above with relation to zero setting assembly 26.6, 26.7. The finger 33.2 can be rotated by rotating spindle 33.5 and spring 33.1 more or less tensioned thereby varying the mutual force between follower arm 32 and crank roller 24.4. The arbor 31 further carries a transfer cam 34 consisting, similar to the detector arm 24 of an eccentric disk 34.1 and a roller 34.4 pivoted at 34.5. This transfer cam cooperates with the actuator lever which will be described below. The rollers 24.4 and 34.4 are made of especially suitable synthetic material such as graphite charged fluorocarbon polymer resins which are very durable and have low friction. Unless the cam roller 24.4 is at dead center on the follower arm 32, the spring motor 33.1 will by way of rotation of arbor 31 and swinging of arm 32 rotate the shaft 21 in one or the other direction, depending on the setting of the detecting means in accordance with the switching program at hand.

The actuator means assembly has a resilient lever arm 41 fastened on an angle mount 42 with one bent up end 43. The mount is screwed to the side wall of the housing by means of the above described zero adjustment assembly with spindle 26:6 and nut 26.7. At its somewhat narrower outer end 44 the resilient lever 41 is contacted by the cam roller 34.4 of the transfer assembly. Approximately in the center of the lever 41 is mounted an operator member such as button 46 which, upon downward deflection of the lever depresses the common switch spring of the circuit making and breaking device to be described herein below.

The switch means proper is in the present embodiment of the type described in my above-mentioned Patent No. 2,825,778. As shown in FIGS. 3 and 4, it has a base 51,

two fixed contact springs 52, 53, a movable contact spring 54, and three threaded terminal post rivets 52.1, 53.1, and 54.1. The switch is shown in normally closed condition of contact 53 (NO) and normally open position of contact 52 (NC) with the COMMON contact 54 on 53. Depression of operator 46 transfers contact of 54 from 53 to 52. The base 51 is fastened to the housing 10, as shown in FIG. 4, by means of two bolts 51.1 and 51.2 which are screwed into tapped holes of a plate 55. These bolts reach through round perforations of the base 51 (FIG. 3) and also through two holes 51.5, 51.6 of the housing 10 (FIG. 4). 51.6 is a long hole as indicated in FIG. 1. By loosening 51.2 with head 58.2 the complete switch can be rotated on 51.1 with head 58.1 for the purpose of contacting adjustment. This adjustment is indicated by means of the pointer 58 which plays on a scale 59 as shown in FIG. 1. It will be evident that three flexible wires can be brought from terminals 54.1, 52.1 and 53.1 through the bushing 125 (FIG. 1). This bushing can be sealed so that together with the other seals mentioned above the switch can be completely sealed.

The basic operation of the above-described switch will now be explained, and this will be followed by a description of some modes of operation and of the various adaptations and adjustments possible.

Rotation of the feeler arm 23, whether angularly limited or continuous in either direction, rotates the shaft 21 and the detector cam 24 with its roller 24.4. This causes swinging movement of the follower arm 32 which is pressed against the detector cam by the spring or other motor means such as 33.1. Upon removal of the detected force which rotates the feeler, the spring will return'the feeler to initial zero position within ranges determined by the setting of the angle stop '29, if it is used. Up to the dead center position of roller 24.4 on follower 32, corresponding to about deflection of the feeler, the spring 33.1 is able to return the feeler to zero position. If greater angles, or a continuously rotating feeler (with zero and angle stops removed) are used, the spring 33.1 would be ineffective for return movement and a modification such as described below with reference to FIG. 6 is used. The follower 32 rotates the arbor 31 which in turn rotates its transfer cam 34 with roller 34.4. The latter, in many instances after a predeterminable period of pretravel, contacts the arm 41 of the actuator component or assembly, moving the actuator pusher 46 against the resilient contact arm 54 which, depending on the adjustment to be described herein below, may initially be set on either fixed contact 52 or 53 or therebetween, for normally open or normally closed single throw operation or for connection transferring double throw operation. One such transfer operation is performed during any one angular motion of the feeler, or during a complete rotation of the shaft 21.

Within the above sequence of basic motions, the following adaptations, adjustments and modifications are feasible, it being understood that these are not the only possible ones in view of the large number of possible combinations between such adjustments and adaptive adaptations which are possible without structural changes.

Electrical contact switching is carried out within each swinging movement of the feeler arm within a predetermined angle, or within each total revolution if that mode of operation is used.

By suitable means, for example tapped holes in the back wall of the housing, the switch is fastened at a suitable point, such as in the path of a moving object fed into or discharged from a machine, or in the path of a moving component of a machine or an operator fastened thereto for this specific purpose. By way of example, the feeler 23 can for example be placed in the path of baked good units discharged from an oven, the switch serving the purpose of controlling a related operation. In the other principal mode of use, the feeler can be placed into the path of a reciprocating or rotating part for example of a punch press or machine tool. In such embodiments, the feeler movement can be limited to definite angle positions from which the feeler will return. In other embodiments, the switch may be used for control by a continuous rotation. In the latter instance the feeler blade can be removed and the head 22 coupled to a shaft or similar means of the machine from which controlling movement is derived or to which controlling movement is applied. As mentioned above, the feeler arm itself can be either a flexible blade or a stiff rod or even a vane alfected by fluid or gaseous currents. It can be inclined or shortened by loosening its set screw 22.1 and by moving it within its slot 21.2. Slanting of the feeler and extension thereof to both sides are thus possible in addition to removal for direct rotational operation.

For operation within a given angle, a zero position is established by means of the stop rod 26.5 placed as shown in FIGS. 2 and 3 and so adjusted at 26.7 that it contacts one of the zero stop wings 26.1, 26.2 (FIG. 5) to define the zero angle position of the feeler. The feeler excursion angle from the zero position can be limited by properly positioning the angle stop nose 29.21 into the path of pin 28, by means of the screws 29.1, 29.2 and 29.3. For eliminating these angular restrictions, the stop rod 26.5 can be turned out of the path of the wings 26, and the angle stop 29 or the pin 28 can be made ineffective simply by unscrewing them.

The basic position of the detector feeler can be varied several degrees clockwise or counterclockwise from precise zero by changing the adjustment of the zero stop rod 26.5 thus providing a precise starting point.

The relative angular positions of feeler hub 22, and of the two cams 24 and 34 can be conveniently varied by means of the Allen set screws 22.1, 24.2 and 34.2, for determining a definite relation between a timing cycle as a whole and the switch contact operation within that cycle.

As'meutioned above, the feeler means such as the blade 23 can be of varying length; 6" is standard but this dimension can be increased to 12 and more without detriment to proper operation. As likewise mentioned above, the blade, rod, vane, or other feeler component can be shifted within the slot 21.2. The blade or rod can be actuated from either or both ends, clockwise or counterclockwise, and for that purpose two zero adjustment wings 26.1 and 26.2 are provided.

It will be understood that in the position of the stop nose 29.2 for example at 90 (FIG. 1), and the blade being further contacted by the supervised or control effecting body, the blade will bend backwards until released and then returned into zero position as determined by the zero stop rod and spoke structure.

The double cam construction according to the invention introduces a certain leverage which results in adjustable pretravel and overtravel of the contact switching as compared to the originally detected, controlling mechanical impact on the feeler. The adjustability of the collar and of both cams, together with the possible adjustment of the switch itself, permit further variation of predetermined travel after and before the predetermined actual contact switching.

The sensitivity of the switch according to the invention can be controlled by the sensitivity adjustment assembly 33.2, 33.5, shown at the righthand side of FIGS. 2 and 3. The degree of adjustment can be indicated if desired with a scale on the front of the housing as shown at 59 in FIG. 1. The sensitvity can be varied from a minimum corresponding to the feeler weight, to several ounces of control pressure on the arm. The sensitivity is further variable by the use of springs of various tensions which can be easily interchanged by means of bolt assembly 33.7.

As mentioned above, the spring 33.1 is able to return the follower 32 only up to a position when roller 24.4 reaches its dead point thereon. Beyond that point, the spring would tend to turn the follower in opposite direction. Thus, spring 33.1 is useful only within feeler deflection angles smaller than which are those that are most commonly used. For larger angles, up to somewhat smaller than 360 and for continuous rotation, a different motor means is used such as the spiral or clock type spring shown in FIG. 6. In this figure all parts are exactly the same as in FIG. 3 with the exception of spring 33.9 which is at one end fastened to cam body 24.1 such as at 24.2, t-hen wound around that body a required number of turns, then stretched tangentially towards and fastened to sensitivity adjustment rod 32.2. It will be evident that only an easily performed interchange of two parts but no structural modification is required for this adaptation and that the sensitivity adjustment is the same for both types of springs. The spiral spring 33.9 could be used for all deflection angles of the feeler 23, but the helical spring 33.1 is less expensive and hence preferred for the frequently used small angle detecting deflections.

The contact position of the switch assembly is variable by means of the adjustment pointer 58 and scale 59. Upon loosening the screw 51.2 the switch base can be rotated on the center defined by screw 51.1. Switches of the type herein described and preferably used in the device according to the invention have no inherent bounce and their full area Phosphor bronze blades adequately conduct heat from their silver contacts which have good wiping action which increases the switch life. It will be evident that the contact terminal construction provides for exceptionally good clearance, convenience of handling, and security against strain, and can be fully sealed.

It will be evident that the above-described switch unit and cam adjustments permit the easy and unequivocal setting of any desired contact make and break relation together with predetermined pretravel and overtravel in relation to the controlling feeler movement as translated through the cam and actuator train.

It will also be apparent that adjustment of the cams or replacement of the complete switch assembly can be easily accomplished by removing a cover and by loosening the zero adjustment assembly at 26.7. The elimination of the zero setting, for purposes of continuous rotary operation is similarly accomplished by loosening'the connection at 26.7 and rotating the spindle 26.6 by way of its Allen socket. Removal and replacement of the switch unit is accomplished very easily by means of screws 51.1 and 51.2 with heads 58.1 and 58.2 which, as mentioned above, also serve for adjusting the switch position. It will be observed that for minimal contact pretravel transfer the pointer 58 has to be raised whereas it is lowered for maximum contact pretravel transfer.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim: 1. A switching device comprising: mounting frame means; detector means including a shaft pivoted on said frame means, feeler means laterally extending from the shaft, and detector cam means on the shaft;

transfer means including an arbor pivoted on said frame means, follower means fixed to the arbor and contacting said detector cam means for rotating the arbor on rotation of said shaft, motor means for maintaining contact between follower means and de tector cam means and capable of rotating said shaft by way of the follower means and the detector cam means, and transfer cam means on the arbor;

switch means mounted on said frame means and having a resilient contact arm; and

switch actuator means mounted on said frame means, havin resilient lever means positioned for deflection by said transfer cam means, and having an operator member juxtaposed to said contact arm for deflecting it upon rotation of said detector cam means by said feeler means.

2. Device according to claim 1 wherein said feeler means include a flexible blade, and a collar adjustably fastened to said shaft and having a diametrical slot for said blade.

3. Device according to claim 1 wherein said detector means include zero stop means having a stop wing fastened to said shaft and a stop rod adjustably fixed to said frame means for projecting in the path of said wing.

4. Device according to claim 1 wherein said detector means include angle stop means having a pin fastened to said shaft and a stop nose capable of being fastened to selected points of said frame to extend into the path of said feeler means to limit its angular travel to selected angles.

5. Device according to claim 1 wherein said follower means includes rod means with two arms extending from opposite sides of said arbor, said detector cam means contacting one arm and said motor means being attached to the other arm.

6. Device according to claim 5 wherein said motor means is a spring attached between said other arm and said frame means, and which further includes means on the frame means for adjusting the spring tension.

7. Device according to claim 1 wherein said switch means includes base means for mounting said contact arm and means for tilting said base means on an axis perpendicular to the contact arm.

8. Device according to claim 1 wherein said detector cam means and said transfer cam means are rotatably adjustable on said shaft and said arbor respectively.

9. Device according to claim 1 wherein said mounting frame means includes a housing open at both ends, means for attaching to said housing said detector means, said transfer means, said switch means and said actuator means, and two covers one for each open side of said housing and one of said covers having means for leading conductors to said switch means.

10. Device according to claim 9 wherein said housing is of rectangular cross section, and includes on the insides of opposite walls two bearing blocks for said shaft and said arbor, one of said Walls having an opening aligned with said shaft which extends through said opening.

11. Device according to claim 10 wherein one of said walls has two windows, one opposite the contacts of said switch means and the other located for illuminating the switch means from the outside.

12. Device according to claim 10 wherein said switch means includes base means, and wherein said base means is fastened with two bolts to one of said walls, said wall having one round and one long hole for said bolts, and the base being capable of swinging about the bolt in the round hole.

13. Device according to claim 10 wherein said wall of the housing has two openings near respective side walls, and said detector means and said transfer means each include a spindle having a threaded reduced end with a tool engageable face and extending from a spindle shoulder through a respective wall opening, and a nut engaging the respective threaded end on the outside of the wall.

14. Device according to claim 12 further including on the outside of said wall an index pointer with two round holes each engaging a respective one of said bolts to swing with said base upon adjustment thereof.

15. Device according to claim 1 wherein said motor means is a spring exerting linear tension between said detector cam means and said frame means.

16. Device according to claim 1 wherein said motor means is a spring exerting linear tension between said follower means and said frame means.

17. A switching device comprising:

a housing having two bearing blocks on opposite walls thereof;

detector means including a shaft pivoted in said blocks, and extending beyond one of the blocks through an opening of the housing, a collar adjustably mounted on said shaft on the outside of the housing, a feeler blade laterally extending from the collar, and detector cam means on the shaft;

transfer means including an arbor pivoted on said blocks parallel to said shaft, a follower rod extending laterally from the arbor and contacting said detector cam means for rotating the arbor on rotation of said shaft, spring means for maintaining contact between follower rod and detector cam means and capable of rotating said arbor and said shaft by way of the follower rod and the detector cam means, and transfer cam means on the arbor;

switch means mounted on said housing and having a plurality of parallel contact arms extending between said opposite walls; and

switch actuator means mounted on said housing, having a resilient lever parallel to said contact arms, positioned for deflection by said transfer cam means, and having an insulating projection juxtaposed to one of said contact arms for deflecting it upon rotation of said detector cam means by said feeler blade means.

18. Device according to claim 17 wherein said switch means is mounted on one of said opposite walls of the housing which wall has a round and an oblong hole, with two bolts extending from the switch means through the wall openings, such that switch means can be rotated around the bolt through the round hole.

19. Device according to claim 17 wherein said arbor has a spring rod extending laterally therefrom and wherein said spring means is a helical spring fastened between said spring rod and said housing.

20. Device according to claim 17 wherein said detector cam means has a cylindrical portion and wherein said spring means is a spiral spring fastened at one end to, and wound around, said cylindrical portion and fastened at the other end to said housing.

References Cited UNITED STATES PATENTS 2,200,570 5/1940 Zint 20061.4 1 X 2,906,842 9/1959 Brin 200153 X 3,202,001 9/1965 Gauvreau 200-47 X 3,300,598 1/1967 Scott et a1. 200-47 BERNARD A. GILHEANY, Primary Examiner.

H. E. SPRINGBORN, Assistant Examiner, 

1. A SWITCHING DEVICE COMPRISING: MOUNTING FRAME MEANS; DETECTOR MEANS INCLUDING A SHAFT PIVOTED ON SAID FRAME MEANS, FEELER MEANS LATERALLY EXTENDING FROM THE SHAFT, AND DETECTOR CAM MEANS ON THE SHAFT; TRANSFER MEANS INCLUDING AN ARBOR PIVOTED ON SAID FRAME MEANS, FOLLOWER MEANS FIXED TO THE ARBOR AND CONTACTING SAID DETECTOR CAM MEANS FOR ROTATING THE ARBOR ON ROTATION OF SAID SHAFT, MOTOR MEANS FOR MAINTAINING CONTACT BETWEEN FOLLOWER MEANS AND DETECTOR CAM MEANS AND CAPABLE OF ROTATING SAID SHAFT BY WAY OF THE FOLLOWER MEANS AND THE DETECTOR CAM MEANS, AND TRANSFER CAM MEANS ON THR ARBOR; SWITCH MEANS MOUNTED ON SAID FRAME MEANS AND HAVING A RESILIENT CONTACT ARM; AND SWITCH ACTUATOR MEANS MOUNTED ON SAID FRAME MEANS, HAVING RESILIENT LEVER MEANS POSITIONED FOR DEFLECTION BY SAID TRANSFER CAM MEANS, AND HAVING AN OPERATOR MEMBER JUXTAPOSED TO SAID CONTACT ARM FOR DEFLECTING IT UPON ROTATION OF SAID DETECTOR CAM MEANS BY SAID FEELER MEANS. 